What's the matter with my Frazier Fir?

If you had it indoors for months, and then suddenly put it into the sun, it will shock it, or sunburn it.

Plants that have been inside, need to be transitioned to outside conditions slowly, in a process called "hardnening off", where you put it in sun for maybe 2 hours, then bring it in. Each day you increase the time spent in the sun, until after a week or so, they can be outside all day (and night) long.

Go ahead and plant it, and see if it grows through the damage. You've got nothing to lose by trying. Water maybe once a week this summer, in hot weather.

My mother bought a small potted Frazier fir at Christmas. She probably maintained it indoors for a couple months, then put it outdoors as the weather got nicer and she began her spring gardening. It hasn't been doing well; although it has gotten plenty of sun and rain, the tips of its boughs are turning brown. She was going to throw it away, so I took it home with me, hoping to rescue it and put it in my own yard. It's about 24" tall. Although I haven't planted it yet, it is in a sunny spot, and it has gotten watered by the 2-3 rain events we've had in the past week. Why is it turning brown? What should I do to help it? I'm in Zone 7 if it makes a difference.

What?